What The Evidence Reveals About Midfoot Ulcers In Patients With Diabetes

Given the long-term challenges with conservative care and high recurrence risk associated with diabetic midfoot ulcers, this author examines the literature on surgical procedures including the exostectomy and realignment arthrodesis.

Midfoot ulcerations represent a challenging endeavor for podiatric physicians. Midfoot ulcers are reportedly responsible for approximately 40 percent of lower extremity amputations due to their notorious difficulty in healing and their high rate of recurrence.1-3

The etiology of midfoot ulcerations in patients with diabetes is most commonly active or inactive midfoot Charcot deformity. When destruction centers on the tarsometatarsal joint, this is a Brodsky Type I Charcot deformity. The tarsometatarsal joint is the most common location of occurrence, comprising approximately 60 to 70 percent of Charcot foot deformities.4 Without prompt and accurate detection, and rapid immobilization of acute Charcot, subluxation and dislocation can quickly lead to fracture and destruction. This results in the loss of the osseous architecture of the foot and the classic “rocker bottom” foot deformity associated with Charcot.1

The skin and subcutaneous tissues in areas of the plantar foot that are typically non-weightbearing are not specialized for sustained weightbearing. Osseous prominences in these areas are now subject to increased pressure and shear strain.1 This leads to rapid callus formation and ulceration, which can quickly result in osteomyelitis given the close proximity of bone beneath the ulcer base. Treatments of these ulcerations range from conservative to surgical, depending on the duration of the wound and associated skin/soft tissue and bone infection.

Conservative measures typically consist of total contact casting until resolution of the ulceration. Casting should continue at least seven to 14 days beyond the date the ulceration has healed in order to allow for maturation of the newly epithelialized wound. The patient must then wear custom orthotics and custom shoe gear with or without adjunctive lower extremity bracing to minimize the potential for ulceration recurrence.

Pinzur reported on 147 patients with midfoot Charcot deformity to determine if successful treatment could occur with conservative measures alone.5 The author defined success as the patient having no ulcerations and the ability to remain ambulatory in over-the-counter shoe gear with custom inserts. The reasoning for this was that custom shoe gear takes a minimum of four weeks for production, leaving the patient without these protective devices for that duration. The follow-up time of the study was 12 months. The average patient age was 56.4 years.

Pinzur found that 87 patients (59.2 percent) treated in this manner did not require surgical intervention.5 However, physicians had to follow the patients on a routine basis to provide patient education and monitor for potential recurrent breakdown. Patient education should consist of explaining the need for diligence in maintaining a dedicated daily routine of below the knee hygiene, foot/nail/callus care and the use of orthotics/shoes/braces for each and every step inside and outside of the house. This can be a difficult endeavor for patients to maintain for a lifetime in order to minimize ulceration recurrence.6,7

Given the difficulty of long-term success with conservative treatment measures, podiatric surgeons have utilized surgical intervention targeted at the osseous prominences that can cause calluses and subsequent ulceration. The goal of surgery is to create a stable, plantigrade foot that is free from areas of plantar osseous prominence in order to minimize the potential for ulceration. Surgical treatment ranges from exostectomy and reconstruction to realignment arthrodesis of the foot.

A Closer Look At The Efficacy Of Exostectomy

One may utilize exostectomy to resect the osseous prominence of the plantar foot to minimize ulceration. This procedure works best in patients with a stable, inactive Charcot deformity. The surgeon can utilize a direct or indirect approach. An indirect approach involves making the surgical incision on the medial or lateral aspect of the foot above, and adjacent to the site of the ulceration. One would then use an osteotome or sagittal saw to resect the osseous prominence. The advantages of an indirect approach are avoidance of a plantar incision and a reduced risk of contamination as the approach is not through the ulceration.1 The surgeon would perform a direct approach through the ulceration or via excision of the ulceration, providing direct access to the bone to be resected beneath.

The difficulty with exostectomy lies in ensuring adequate bone resection to minimize the potential for recurrent ulceration while avoiding excessive resection, which could potentially lead to destabilization of the foot.1,8 There is currently no widely accepted protocol to quantify how much bone to resect. Wieman and colleagues describe a method in which one performs osseous resection with an attempt to “recreate” the arch of the foot.1 With this technique, the surgeon would do osseous resection in a curvilinear fashion, extending distally from the inferior aspect of the first metatarsal to the calcaneus proximally and approximately one-third superiorly into the arch of the foot. Reported complications following exostectomy are a non-healing wound, recurrent ulceration, wound dehiscence, instability necessitating conversion of the exostectomy to arthrodesis, skin/soft tissue infection, osteomyelitis and amputation.1,6,8-10

Wieman and coworkers reported on the results of exostectomy, using the resection technique described above, in 40 patients with 54 diabetic midfoot ulcers.1 The mean age was 60.2 ± 1.8 years. The mean duration of the ulceration was 212 ± 179 days. Surgeons used an indirect approach in all cases. The mean follow-up time was 38 ± 36 months. There were 29 (54 percent) amputations that occurred secondary to combined infection and peripheral vascular disease. The 25 remaining ulcerations took a mean of 129 ± 62 days to heal. There was one wound dehiscence and two recurrent ulcerations.

Brodsky and Rouse reported on 12 patients who all had an indirect approach for eight plantar medial ulcerations and four plantar lateral ulcerations.8 The average patient age was 56. The follow-up time was 25 months. Nine patients went on to successful healing of their ulcerations. Complications consisted of four cases of serous drainage, three cases of delayed healing and one recurrent wound. There were two deaths, both of which were unrelated to the foot. The one patient with a recurrent wound required a Symes amputation after the wound recurred following two exostectomy procedures. This patient previously had incision and drainage of a plantar foot abscess, and subsequent coverage with a split thickness skin graft (STSG). The authors felt the tenuous nature of the plantar skin due to the STSG was the etiology for the recurrent ulceration.

Myerson and colleagues reported on 12 patients who had an exostectomy.11 Eight of these patients were stable and ulcer-free 32 months after the procedure. Complications consisted of conversion to arthrodesis (three patients with two being secondary to instability) and one amputation secondary to infection at three months postoperatively.11

Rosenblum and coworkers reported on the results of exostectomy on 31 patients (32 ulcerations) with an average age of 50.6 years.9 The mean duration of the ulcerations was 12.9 months. The ulceration depths were superficial, probing to bone and deep but not probing to bone. One recurrent ulceration healed at the time of surgery. Surgeons ellipsed ulcerations less than 3 cm in diameter and covered ulcerations greater than 3 cm in diameter by utilizing a local fasciocutaneous flap overlying a flexor digitorium brevis muscle flap. For the recurrent ulceration that healed at the time of surgery, surgeons performed excision via a direct approach.

The follow-up time was 20.8 months. Of the 32 ulcerations, 21 remained healed and 11 were subject to wound dehiscence and ulceration recurrence, which the authors attributed to inadequate bone resection.

Catanzariti and colleagues reported on the use of ostectomy in 20 patients with 28 ulcerations.10 The authors used a direct approach for 21 ulcerations (13 medial and eight lateral) and an indirect approach for six ulcerations (five medial and one lateral). Complications consisted of midfoot instability in one patient, hindfoot/ankle Charcot in one patient, one recurrent ulceration requiring medial plantar artery flap coverage, one soft tissue infection, osteomyelitis in two patients, one non-healing wound, and one below-the-knee amputation (BKA). Complications occurred more often with plantar lateral midfoot ulcerations. The only complication related to a plantar medial midfoot ulceration was the BKA. Twelve (60 percent) patients had successful healing of their ulceration.

Laurinaviciene and coworkers also found a higher incidence of complications related to plantar lateral midfoot ulcerations following exostectomy.6 In their study of 20 patients with 27 ulcerations (18 medial and nine lateral), they found that 17 (94.4 percent) medial ulcerations went on to complete healing in comparison to three (33.3 percent) lateral ulcerations at the average follow-up time of 21.6 months.

Is Realignment Arthrodesis An Effective Option For Midfoot Ulcers?

Due to the potential for unsatisfactory long-term results with exostectomy as well as the instability and significant deformity that can be associated with midfoot Charcot, the recent trend has been toward reconstruction of the foot with realignment arthrodesis.2

Realignment arthrodesis involves the use of a “superconstruct” design as Sammarco described.12 This involves osseous resection for deformity correction and arthrodesis extending beyond the affected joints, utilizing hardware deemed to be the strongest that the soft tissues will allow and that will provide rigid stabilization of the foot.12 Indications for this procedure are a grossly unstable foot, recurrent ulceration, failed conservative treatment or failed surgical treatment consisting of a previous exostectomy. The advantage of realignment arthrodesis is the creation of a stable, plantigrade foot leading to a decreased risk of recurrent ulceration.4,12-14

The primary disadvantages associated with realignment arthrodesis are the increased morbidity and mortality associated with the procedure given the longer operative times; the greater potential for complications related to hardware insertion and osseous healing; infection; and the prolonged restrictions on weightbearing. The most commonly reported complications are nonunion, infection, wound dehiscence, osteomyelitis, hardware failure or migration, and recurrent ulceration.

Various authors have also reported major complications consisting of continued fracture and deformity, osteonecrosis, deep venous thrombosis and amputation.12-18

Early and Hansen reported on surgical reconstruction in 10 patients with midfoot Charcot and recurrent ulceration.19 The follow-up time was 28 months. Major complications included two patients with osteomyelitis requiring BKA and one postoperative death secondary to a myocardial infarction on postoperative day three. The remaining seven patients healed with minor complications occurring in only four patients (wound dehiscence in three patients and hardware failure without loss of correction in one patient).

Educating Patients On The Different Treatment Pathways And Associated Risks

The first encounter with a patient who has a midfoot ulceration should involve a frank discussion as to the poor prognosis associated with this ulceration. With this in mind, I discuss the following treatment pathways with the patient.

The first pathway involves patients going against the medical advice of conservative or surgical treatment recommendations, and continuing to self-treat their ulceration. It is important to tell patients that self-treatment will fail to heal the ulcer. If infection occurs, these patients will most likely require hospital admission with a high potential for lower extremity amputation.

The second pathway is conservative treatment consisting of non-weightbearing in a total contact cast followed by strict adherence to a lifelong routine of dedicated lower extremity hygiene, foot care, custom orthotics and the use of customized or custom shoe gear with or without adjunctive bracing. Patients choose this pathway knowing that the potential for ulceration recurrence, future surgical intervention and lower extremity amputation is high.

The third pathway is exostectomy followed by the aforementioned lifelong precautions. Patients choose this knowing that the potential for ulceration recurrence and lower extremity amputation is high.

The fourth pathway is partial amputation of the foot to eradicate the deformity that resulted in ulceration.

The fifth pathway is surgical reconstruction of the foot with education on the prolonged postoperative recovery course and weightbearing restrictions (six to 12 months), and the high risk of associated complications. Following this, patients take the same lifelong precautions and have the potential for lower extremity amputation I previously mentioned.

The sixth pathway is primary below-the-knee amputation.

No matter what treatment pathway the patient chooses, one should discuss the potential risks for significant complications to occur, primarily below-the-knee amputation. Physicians should also emphasize the importance of lifelong precautionary measures including a daily below-the-knee hygiene protocol, routine foot/nail/callus care and the use of proper orthotics, shoe gear and/or bracing.

Emphasizing The Need For Family Involvement And Multidisciplinary Teamwork

The treating physician should involve the patient’s family and support network in these discussions so they are also aware of what treatment entails. One should also discuss ease of accessibility of a wheelchair, walker, crutches, etc., in the patient’s home and potentially his or her place of employment. Does the patient need to use any stairs? Are all areas where the patient must go wheelchair accessible?

A consult to physical therapy can be beneficial in having these patients properly trained in the safe use of assistive ambulation devices to maintain their weightbearing restrictions safely. One should consider short postoperative hospitalization in patients who have extensive surgical intervention. Hospitalization ensures patient safety postoperatively and reinforces proper techniques for non-weightbearing and antithrombotic prophylaxis if patients use prophylaxis in the postoperative period.

The podiatric physician should consider consults with wound care clinics, physical therapy, social work and rehabilitation or skilled nursing facilities during the postoperative recovery of these patients for optimal patient care.

Dr. Schade is the Chief of the Limb Preservation Service and Director of the Complex Lower Extremity Surgery and Research Fellowship at Madigan Healthcare System in Tacoma, Wash. She is an Associate of the American College of Foot and Ankle Surgeons.